Balance between Metal and Ligand Reduction in Diiminepyridine Complexes of Ti
Bibliographic record
Abstract
Reaction of the diiminepyridine ligand Et DIP (2,6-Et 2 -C 6 H 3 N═CMe) 2 C 5 H 3 N) with TiCl 3 (THF) 3 gave the corresponding Ti(III) complex ( Et DIP)TiCl 3 ( 1 ). Reduction of 1 with 1 equiv of KC 8 produced the formally Ti(II) complex ( Et DIP)TiCl 2 ( 2 ). From this, ( Et DIP)TiClR complexes (R = Me ( 3a ), Me 3 SiCH 2 ( 3b ), Ph ( 3c )) were obtained by addition of 1 equiv of RLi. Similarly, dialkyl complexes ( Et DIP)TiR 2 (R = Me ( 4a ), Me 3 SiCH 2 ( 4b )) were obtained with 2 equiv of RLi. All new complexes except 3b were characterized by single-crystal X-ray diffraction. EPR studies indicate that complex 1 is best regarded as a true Ti(III) complex with an “innocent” DIP ligand. Complexes 2 – 4 are all diamagnetic. In contrast to DIP complexes of the late transition metals Fe and Co, the new complexes 2 – 4 show strong upfield 1 H NMR shifts for the pyridine β and γ protons caused by transfer of negative charge to the DIP ligand. On the basis of this and the C═N and C imine –C Py bond lengths, a description involving Ti(IV) and a dianionic ligand seems most appropriate, and DFT calculations support this interpretation. This means that reduction of Ti(III) complex 1 results in oxidation of the metal center to Ti(IV). VT-NMR studies of 4a suggest a small and temperature-dependent thermal population of a triplet state, and indeed calculations indicate that 4a has the lowest singlet–triplet energy difference of the systems studied.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".